Long after her cult statues stopped being carved, Tyche survived inside a technical apparatus far removed from temple ritual: Hellenistic and later astrology. The Lot of Fortune, known in Greek as the Kleros tes Tyches and in Latin as the Pars Fortunae, is not a planet or a star but a calculated point in a horoscope, derived by measuring the zodiacal distance between the Sun and Moon and projecting that same distance from the rising degree, with the exact formula reversed for charts cast at night. Astrologers such as Vettius Valens, writing his lengthy Anthology in the second century CE, gave the Lot of Fortune sustained treatment as a marker of a native's material fortune, health, and bodily life, treating Tyche's old civic role as protector of prosperity as something a mathematician could now locate at a precise degree rather than something a city petitioned with sacrifice. Claudius Ptolemy's Tetrabiblos, more skeptical of the proliferating lots that later astrologers multiplied by the dozen, still retained the Lot of Fortune as one of the few worth calculating, a rare point of agreement across an otherwise contentious astrological literature.
The abstraction is a telling one: Tyche the sculpted, city crowned goddess of the Hellenistic squares became, in this parallel tradition, a piece of arithmetic embedded in the horoscope itself, and the Lot of Fortune remains in use among astrologers working in the Hellenistic revival today, an unbroken thread of technical practice considerably older than her more famous statues.